In the neurophysiological literature with non-human primates, much effort has been devoted to understanding how reward expectation shapes decision making, that is, the selection of a specific course of action. On the other hand, we know nearly nothing about how reward shapes attention, the selection of a source of information. And yet, understanding how organisms value information is critical for predicting how they will allocate attention in a particular task. In addition, it is critical for understanding active learning and exploration, behaviors that are fundamentally driven by the need to discover new information that may prove valuable for future tasks.

To begin addressing this question we examined how neurons located in the parietal cortex, which encode the momentary locus of attention, are influenced by the reward valence of visual stimuli. We found that reward predictors bias attention in valence-specific manner. Cues predicting reward produced a sustained excitatory bias and attracted attention toward their location. Cues predicting no reward produced a sustained inhibitory bias and repulsed attention from their location. These biases were persisted and even grew with training, even though they came in conflict with the operant requirement of the task, thus lowering the animal's task performance. This pattern diverges markedly from the assumption of reinforcement learning (that training improves performance and overcomes maladaptive biases, and suggests that the effects of reward on attention may differ markedly from the effects on decision making. I will discuss these findings and their implications for reward and reward-based learning in cortical systems of attention.